Compressed Air Maintenance Unit and Consumer Control Device Equipped with the Same

ABSTRACT

A compressed air conditioning apparatus ( 2 ) and a load control device ( 1 ) equipped therewith are proposed, the compressed air conditioning apparatus ( 2 ) comprising a switch-on valve ( 14 ) with 3/3-valve functionality. By means of the switch-on valve ( 14 ), an outlet passage ( 22 ) leading to a load device (A) can, among other aspects, be optionally supplied with compressed air or disconnected from the compressed air supply. By means of a pressure sensor ( 24 ) and/or a flow sensor ( 25 ), actual pressure and/or flow data can be recorded and compared to reference data previously stored in a teaching mode. As a function of the comparison result, an electric diagnostic signal can be generated, offering, among other aspects, the opportunity for monitoring leakage from the load device (A) or excessive air consumption.

The Invention relates to a compressed air conditioning apparatuscomprising the following components:

-   -   an electrically actuated switch-on valve which comprises a feed        inlet connectable to a compressed air source, a vent outlet        connected to the atmosphere and an operating outlet and which        can be switched into a working position connecting the operating        outlet to the feed inlet and into a venting position connecting        the operating outlet to the vent outlet,    -   an apparatus outlet connectable to an external load device and        connected to the operating outlet of the switch-on valve via an        outlet passage,    -   a pressure sensor suitable for measuring the outlet pressure        prevailing in the outlet passage and/or a flow sensor suitable        for measuring the output flow prevailing in the outlet passage,    -   and an internal electronic control unit which is connected in        terms of signalling technology to the switch-on valve and to the        pressure sensor and/or the flow sensor and which can be operated        in a monitoring mode.

The invention further relates to a load control device suitable forcontrolling a load device, which is equipped with at least onecompressed air conditioning apparatus of the type referred to above andwith an electronic control device connected or connectable thereto.

Prior art designed in the above sense is known from DE 19746179 C2. Thispublication describes a compressed air conditioning unit which isfluid-connectable to a load device to be supplied with compressed air.The compressed air conditioning unit is composed of a plurality ofmodules which can be lined up in any sequence or number. One module ofthe known compressed air conditioning unit is designed as a monitoringmodule which comprises an electronic central unit and can be connectedto an external bus system via a suitable interface. The monitoringmodule may be fitted with indicating and control elements or mayalternatively be provided with a diagnostic and control interface for anexternal indicating and control device. A pressure sensor for pressuredetection is connected to the central unit in the monitoring module. Afurther module of the compressed air conditioning unit may be a flowmeter module for measuring the air flow rate. Finally, the knowncompressed air conditioning unit comprises a switching valve moduleprovided with a switch-on valve, by means of which the compressed airfed in at the inlet can either be let in or blocked. Switch-on valvesfrequently also have a three-way function, so that, if the compressedair is blocked, they adopt a venting position in which the operatingoutlet is connected to the atmosphere, so that the outlet passageadjoining the operating outlet including the load device connectedthereto is vented.

From DE 102004005982 B3, a compressed air conditioning apparatus isknown which is made up of a plurality of modules, which may for exampleinclude a switch-on valve, a flow meter, a control module or amonitoring module. Sensor devices for pressure or flow detection mayalso be provided.

DE 10355250 A1 describes a method and an associated device for leakdetection in an operating device equipped with an operating cylinder.The device includes a pressure sensor detecting the pressure of thepressure fluid, a loss of pressure fluid being detected on the basis ofpressure fluctuations. In addition, a flow sensor installed into thesupply lines detects the flow rate of the flowing pressure fluid,wherein, on the basis of a physical equation, the measured pressurevalue and the measured flow rate are brought into a specificrelationship to one another in order to determine any existing leakageon this basis.

From WO 95/19589 A1, the use of a monitoring device for monitoringcyclically operating systems is known.

Compressed air conditioning units of the type referred to above aregenerally fitted with switch-on valves having two possible switchingpositions. A first switching position is conceived as a working positionand establishes a connection between the feed inlet and the operatingoutlet and thus a connected external load device. In the secondswitching position, the feed inlet is disconnected from the operatingoutlet. If the second switching position is a venting position, theoutlet passage is simultaneously vented together with the external loaddevice connected thereto. Other types of switch-on valves completelyblock the outlet passage in the second switching position, makingventing impossible. The venting function, however, is an importantaspect of the compressed air supply of any connected load device.

A disadvantage of compressed air conditioning apparatus of the presenttime, the switch-on valve of which has a venting position, lies in thefact that air is consumed unnecessarily while the connected externalload device is inoperative. If the switch-on valve remains in theworking position, compressed air is continuously pushed at high pressureinto the outlet passage irrespective of the non-operation of the loaddevice, and this air is lost owing to unavoidable leakage. If theswitch-on valve is switched into the venting position, on the otherhand, the outlet passage and the load device connected thereto areemptied completely, with the result that the emptied passage system hasto be refilled completely when the load device is restarted. In terms ofenergy efficiency, such circumstances accompanying the start of externalloads are no longer in keeping with the times.

The present invention is based on the problem of providing measuresfacilitating the energy-efficient operation of air-operated loaddevices.

To solve this problem, it is provided in a compressed air conditioningapparatus of the type referred to above

-   -   that the switch-on valve has a 3/3-valve functionality and can        additionally be switched into a blocking position in which its        operating outlet connected to the apparatus outlet is isolated        both from the feed inlet and from the vent outlet,    -   that the internal electronic control unit can in the blocking        position and/or in the working position be operated in a        teaching mode as an alternative to the monitoring mode, in which        teaching mode a time-dependent pressure drop of the outlet        pressure can be determined in the blocking position and/or a        time-dependent flow profile of the outlet flow rate can be        determined in the working position and these values can be        stored in the form of reference data in storage means of the        internal electronic control unit,    -   that the internal electronic control unit comprises comparator        means whereby actual data supplied by the pressure sensor and/or        the flow sensor during the monitoring mode can be compared to        the relevant reference data,    -   and that the internal electronic control unit comprises        outputting means which can output a diagnostic signal as a        function of the comparison result of the comparator means.

The problem is further solved in a load control device which comprises acompressed air conditioning apparatus of this design and an externalelectronic control device connected or connectable thereto.

The inventive idea includes that the compressed air conditioningapparatus may be equipped both with a pressure sensor and with a flowsensor or—depending on the type of monitoring required—with a pressuresensor or a flow sensor only.

The term “flow” is here used to represent in a simplified fashioninherently correct terms such as “volumetric flow rate”, “flow rate” or“throughput” and indicates a flow value per unit of time.

A special measure of the invention is the aspect that the switch-onvalve having a three-way function is designed as a 3/3-way valve and canadopt three alternative switching positions. In this context, it isadvantageous that, in addition to the working position provided asstandard, a venting position or a blocking position can be selected inorder to either discharge the compressed air present in the outletpassage and in the external load device connected thereto completely orto keep it as an enclosed volume during temporary interruptions in theoperation of the external load device. Without losing the advantages ofa venting facility, both an excessive leakage and the unnecessaryemptying of the outlet-side passage system can therefore be avoidedduring a temporary stop of, for example, a machine acting as a loaddevice. This allows for energy-efficient operation.

A further contribution to increased efficiency is provided by theinternal electronic control unit, which can optionally be operatedeither in a teaching mode or in a monitoring mode. The latterfacilitates the output of an electric diagnostic signal for general useif the internal pressure sensor and/or the flow sensor of the compressedair conditioning apparatus detect(s) pneumatic conditions which deviatefrom the values expected or tolerable in normal operation. Suchdeviating operating states may for example be leakage from of amalfunction of components of a connected external load device.Monitoring is made particularly effective by providing that the internalelectronic control unit—in particular in combination with the initialstart-up of a connected external load device—can be operated in ateaching mode for recording individual reference data for pressureand/or flow, which can in the subsequent operation of the system be usedfor comparison to actually measured data in a monitoring mode of theinternal electronic control unit. The monitoring functionality of thecompressed air conditioning apparatus can therefore be adapted to therespective application very flexibly.

Using the pressure sensor, it is in particular possible to monitor thedrop in the outlet pressure in the blocking position of the switch-onvalve and, if this pressure drops too fast, to output an alarm signalfollowing a comparison with the taught reference data. This facilitatesleakage monitoring in the external load device, which may for example berepresented by a machine.

Using the data supplied by a flow sensor, conclusions can be drawnregarding an increased air consumption of the connected external loaddevice in the working position of the switch-on valve, for example asoverall information relating to a whole operating cycle of the loaddevice or relating to specific sub-cycles of the operating cycle.

The compressed air conditioning apparatus is preferably designed as aself-supporting unit with all of its components being integrated,resulting in an extremely compact compressed air conditioning apparatuswhich can easily be integrated into existing pneumatic systems.

If the compressed air conditioning apparatus is equipped with a flowsensor which determines the flow rate on the basis of detected pressurevalues, in particular on the basis of detected pressure differentials, apressure sensor belonging to the flow sensor can also be used aspressure sensor for the detection of the outlet pressure prevailing inthe outlet passage. In this case, there is no need for a separatepressure sensor.

The compressed air conditioning apparatus is expediently directlyprovided with visual display means and/or with audible warning meanswhich can be actuated on the basis of an electric diagnostic signalgenerated by the outputting means in order to indicate operatingproblems directly on site.

The compressed air conditioning apparatus is expediently designed suchthat the electric diagnostic signal it generates can be processedexternally. For this purpose, the compressed air conditioning apparatuscan be provided with at least one communication interface to which canbe connected an external electronic control device which in particularacts as a host and/or an electronic data reader and/or at least onefurther external electronic device. There may for example be twocommunication interfaces of which one can be used for communication withthe external electronic control device, while the other can be used asdiagnostic interface for connection to the data reader. The respectivecommunication interface is preferably of an electromechanical type,which facilitates a very secure signal transmission, in particular viaan electric cable connectable thereto. At least one of the communicationinterfaces is preferably designed as a bus interface, which allows theconnection of a bus leading to an external electronic control device;any bus standards can be used.

In an alternative embodiment, at least one communication interface isconfigured for wireless signal transmission, in particular for faultindication via a cellular radio system, and/or for any other wirelessnetwork connection.

In a particularly advantageous embodiment, the at least onecommunication interface is designed such that a bidirectional signaltransmission is possible.

At least one communication interface can be designed for inputtingand/or outputting binary and/or analogue signals. Such a communicationinterface is in particular provided in addition to a communicationinterface designed as a bus interface.

The switch-over commands for the switch-on valve are expedientlysupplied to the compressed air conditioning apparatus from the outsideand come from the connected external electronic control device. In thiscase, the internal electronic control unit only has to act as atransmitter of switch-over signals without specifically processing thelatter. This reduces the load on the at least one microprocessor of theinternal electronic control unit.

For the activation and/or parameterisation of the teaching mode, thecompressed air conditioning apparatus is expediently equipped withsuitable inputting means. Such inputting means may for example compriseat least one key and/or at least one switch easily accessible on theoutside of the housing of the compressed air conditioning apparatus. Inaddition or alternatively, facilities may be provided for purelyelectric teaching, for example via a special user interface or by meansof an external electronic control device which generally communicateswith the compressed air conditioning apparatus; for this purpose, thecompressed air conditioning apparatus can be provided with at least oneelectric interface which may in particular be represented by thecommunication interface referred to above.

The current data required in the monitoring mode of the internalelectronic control unit are expediently recorded at the same timeinterval as the reference data recorded in the teaching mode.

In the monitoring mode, the internal electronic control unit records thecurrent data once or repeatedly, or repeatedly at regular intervals,depending on operating conditions.

In addition to mere operation monitoring, the electric diagnostic signalcan be used to initiate specific, in particular safety-relevant,actions. The compressed air conditioning apparatus can for example bedesigned to initiate a switch-over action of the switch-on valve inresponse to the comparison result of the comparator means. A switchingof the switch-on valve into the blocking position can for example beinitiated if no significant flow is detected in the outlet passage foran extended period of time in the working position.

The invention is explained in greater detail below with reference to theaccompanying drawing. The single FIGURE (FIG. 1) is a diagrammaticrepresentation of a preferred structure of a load control deviceaccording to the invention, comprising an integrated compressed airconditioning apparatus according to the invention, which has aparticularly expedient structure.

The load control device identified as a whole by the reference number 1comprises as its main component a compressed air conditioning apparatus2, preferably in the form of a self-supporting unit. This compressed airconditioning apparatus 2 can, if required, be combined with otherconditioning modules, of which one is indicated by dot-dash lines at 3,to form a compressed air preparation device 4. The at least one furtherconditioning module may for example be a pressure control module, afilter module and/or an air drier module.

The compressed air conditioning apparatus 2 has an apparatus housing 5which is illustrated as a frame for simplicity and which supports and/orencloses the further components of the compressed air conditioningapparatus 2.

On the outside of the apparatus housing 5, an apparatus inlet 6, anapparatus outlet 7 and a vent outlet 8 are provided. The apparatus inlet6 is designed for connection to a compressed air source P via a fluidline identified as feed line 12. This compressed air source P is shownin a state in which it is connected to the apparatus inlet 6.

The apparatus outlet 7 is designed for the connection of a fluid lineidentified as operating line 13, which leads to an external load deviceA. The drawing shows a state in which a load device A is connected tothe apparatus outlet 7—for example a machine having severalfluid-operated working components.

The vent outlet 8 communicates with the atmosphere R. For this purpose,a silencer not shown in detail is expediently connected to the ventoutlet 8. Ducted air discharge by means of a connectable fluid line isalso possible.

The compressed air conditioning apparatus 2 is provided with anelectrically actuated multiway valve identified as “switch-on valve” 14on the basis of its function. The switch-on valve 14 is expedientlyaccommodated in the interior of the apparatus housing 5. It has a3/3-functionality, i.e. three ways or ports and three possible switchingpositions. In the illustrated embodiment, it is implemented in the formof a single valve unit, but can also be implemented by the suitableinterconnection of several valve units of lower functionality. Theswitch-on valve 14 is preferably an electro-pneumatically pilot-actuatedvalve, but it could also be designed as a directly electrically actuatedvalve.

The switch-on valve 14 of the illustrated embodiment has a firstswitching position conceived as central position, which is shown in thedrawing. From this, it can be switched into a second or a thirdswitching position by activating one of two electrically actuated valvedrives 15 a, 15 b. The second and third switching positions are in eachcase maintained as long as the associated valve drive 15 a, 15 b iselectrically activated. The electric valve drive 15 a, 15 b is inparticular a solenoid device, but other electric drive means can be usedas well.

The three ports of the switch-on valve 14 form a feed inlet 16, anoperating outlet 17 and a vent outlet 18. The feed inlet 16 ispermanently connected to the apparatus inlet 6 or directly representedthereby. The operating outlet 17 is permanently connected to the ventoutlet 18 or directly represented thereby. The operating outlet 17 isconnected to the apparatus outlet 7 via an internal outlet passage 22 ofthe compressed air conditioning apparatus 2. The outlet passage 22expediently extends in the interior of the apparatus housing 5.

The switch-on valve 14 can adopt a blocking position which in theillustrated embodiment corresponds to the central position adopted inthe non-actuated state. In this position, the operating outlet 17 isdisconnected both from the feed inlet 16 and from the vent outlet 18. Inthis way, the outlet passage 18 is blocked and the fluid volume presenttherein as well as in the operating line 13 and the adjoining passagesystem of the load device A is locked in.

The two other possible switching positions of the switch-on valve 14define a working position and a venting position. In the workingposition, the operating outlet 17 is connected to the feed inlet 16while being disconnected from the vent outlet 18. In the ventingposition, the operating outlet 17 is connected to the vent outlet 18while being disconnected from the feed inlet 16. In this way, the outletpassage 22 and the connected load device A are supplied with compressedair from the compressed air source P in the working position of theswitch-on valve 14 and vented to the atmosphere in the venting position.

While the connected load device A is in operation, the switch-on valve14 is held in the working position. During this time, the load device Acompletes a preset operating cycle once or periodically. This operatingcycle is controlled by an external electronic control device whichcommunicates in a manner not shown in detail with the load device A interms of control technology.

If the load device A is not to operate for an extended period of time,for example at the weekend, the switch-on valve 14 can be switched intothe venting position, so that the load device A is vented and nohazardous situations can develop.

If the load device A is inoperative for a short time only, theswitch-off valve 14 can be positioned in the blocking position. In thisway, the air volume present in the load device A is maintained and isavailable for renewed operation. There is therefore no need for againrefilling the load device A completely with compressed air.

The compressed air conditioning apparatus 2 is provided with a pressuresensor 24 and a flow sensor 25. Both of the sensors 24, 25 areexpediently accommodated in the interior of the apparatus housing 5. Inaddition, both of the sensors 24, 25 communicate with the outlet passage22; in the illustrated embodiment, the pressure sensor 24 is connectedto the outlet passage 22, while the flow sensor 25 is installed into therun of the outlet passage 22.

The pressure sensor 24 is capable of measuring the pressure prevailingin the outlet passage 22, this pressure being referred to as outletpressure in further explanations. The flow sensor 25 is capable ofdetermining the current flow rate of the compressed air flowing throughthe outlet passage 22, i.e. the flow of said compressed air. Thismeasured flow will be referred to as outlet flow in furtherexplanations.

If the measuring principle of the flow sensor 25 is based on pressuredetection, a pressure sensor forming part of the flow sensor 25 can takeover the function of the above pressure sensor 24, so that there is noneed for an autonomous pressure sensor 24.

The compressed air conditioning apparatus 2 comprises an internalelectronic control unit 26, which is preferably accommodated in theinterior of the apparatus housing 5 and which is equipped with at leastone microprocessor or microcontroller. To simplify matters, this will bereferred to as “internal control unit 26” in further explanations.

In tennis of signal technology, the internal control unit 26 isconnected to the valve drives 15 a, 15 b of the switch-on valve 4, tothe pressure sensor 24 and to the flow sensor 25 by internal electricsignal lines 27 of the compressed air conditioning apparatus 2. Theinternal control unit 26 can receive electric pressure values and flowvalues from the pressure sensor 24 and the flow sensor 25 respectivelyand output electric actuating signals to the switch-on valve 14.

The compressed air conditioning apparatus 2 is provided with an electricinterface which is identified as first communication interface 28 infurther explanations for better differentiation and which allows asignalling communication between the internal control unit 26 and theexternal electronic control device 23. The first communication interface28 is in particular located on an outside of the apparatus housing 5 andexpediently connected to the internal control unit 26 via internalelectric conductors 32. The first communication interface 28 ispreferably electro-mechanical in design and in particular designed as aplug-in connection device, so that an external signal cable 33, which isindicated diagrammatically only and which provides a connection to theexternal electronic control device 23, can be connected, in particularreleasably.

As an alternative, the first communication interface 28 can be designedas a wireless interface for communication with the external electroniccontrol device 23, in particular by way of radio signals.

The first communication interface 28 is preferably a bus interface whichis capable of transmitting serial bus signals between the internalcontrol unit 26 and the external electronic control device 23. Like theinternal electric conductors 32, the external signal cable 33 can beimplemented in the form of a serial bus system.

The internal control unit 26 comprises electronic storage means 34,comparator means 35 and outputting means 36. In the storage means 34,pressure values of the outlet pressure measured by the pressure sensor24 and flow values of the outlet flow measured by the flow sensor 25 canbe stored as reference data and preferably as actual values as well. Thecomparator means 35 are capable of comparing stored reference data toactual values which are in particular also buffered or else measureddirectly. The outputting means 36 are capable of outputting an electricdiagnostic signal as a function of the comparison result determined bythe comparator means 35.

The outputting means 36 of the internal control unit 26 preferablyoutput the electric diagnostic signal to the first communicationinterface 28, from where it can be transmitted to the externalelectronic control device 23 for further processing as required.

The electric diagnostic signal can also be transmitted to visual displaymeans 37 of the compressed air conditioning apparatus 2 forvisualisation in a preferred way.

It is further possible to provide the compressed air conditioningapparatus 2 with audible warning means 38 as indicated by broken lines,for example with a buzzer, for outputting an audible warning signal onsite on receipt of a corresponding diagnostic signal.

The internal control unit 26 can be operated in a monitoring mode inwhich it can receive and process measurement signals from the pressuresensor 24 and/or from the flow sensor 25 as actual data. In this way,the internal control unit 26 receives time-dependent current values ofthe outlet pressure and/or outlet flow as actual data. The internalcontrol unit 26 can therefore be designed for outputting these actualdata at the first communication interface 28 and/or at the visualdisplay means 37 either electrically or visually.

In an advantageous way, the internal control unit 26 can, as analternative to the monitoring mode, be operated in a teaching mode.Within this teaching mode, the internal control unit 26 can take up thereference data mentioned above and store them in the storage means 34for further processing.

The compressed air conditioning apparatus 2 is expediently provided withinputting means 42 for activating the teaching mode if required. It mayalso be provided that the system can switch between the teaching modeand the monitoring mode as required by way of these inputting means 42.The internal control unit 26 is preferably equipped with an internalcontrol programme which initiates an automatic switch-over to themonitoring mode as soon as the teaching phase is completed.

The teaching mode can expediently be activated both in the blockingposition and in the working position of the switch-on valve 14. If theteaching mode is active in the blocking position, a time-dependentpressure drop of the outlet pressure prevailing in the outlet passage isrecorded and stored as reference data 43 in the storage means 34. Thismay for example happen in response to pressing or activating a key orswitch 42 a of the inputting means 42 twice at any time intervalpreferred. The internal control unit 26 then records the pressure dropof the outlet pressure over time and forms a reference curve 43 a whichis represented by a straight line in the illustrated embodiment. Theshape of this curve does, however, not affect any subsequent evaluation,because only the absolute value of the pressure drop (p1-p2) in themeasured time interval (t2-t1) is relevant.

By operating in the teaching mode in the working position of theswitch-on valve 14, a time-dependent flow profile Q(t) of the outletpressure in the outlet passage as indicated by the reference number 44 acan be determined and likewise stored in the storage means 34 of theinternal control unit 26 in the form of second reference data 44. Thishappens during the operation of the connected load device A, and theflow profile 44 a representing the second reference data 44 preferablycovers the time of a whole working cycle of the load device A. Thesecond reference data 44 can therefore be envisaged as a curve whichrepresents the current outlet flow at any point in time during a typicalworking cycle.

In the subsequent normal operation of the load control device 1, theinternal control unit 26 operating in the monitoring mode can generatean electric diagnostic signal which indicates the energetic situation ofthe connected load device A from a comparison between the measuredactual data and the first or second reference data 43, 44.

The compressed air conditioning apparatus 2 in particular offers theopportunity for leakage monitoring in the blocking position of theswitch-on valve 14. For this purpose, actual data delivered by thepressure sensor 24 in the blocking position of the switch-on valve 14are recorded by the internal control unit 26 and compared to the firstreference data 43 recorded and stored in the teaching mode. Themeasuring interval for recording the actual data is as long as that usedfor recording the first reference data 43, and this arrangement ismonitored and controlled by a control programme in the internal controlunit 26. If possible, the actual pressure should be measured at anoutlet value of the outlet pressure which is at least approximatelyidentical to that used in the reference pressure measurement, which islikewise monitored by the internal control unit 26. This ensures thatthe data to be compared can be assigned to one and the same operatingstate.

Via the outputting means 36, the internal control unit 26 then forexample initiates the output of a diagnostic signal if the pressure dropof the outlet pressure determined in the monitoring mode falls below thereference value recorded in the teaching mode by a preset tolerancevalue.

The measurement of the actual data can be coupled to the switch-overprocess of the switch-on valve 14. The actual data can for example berecorded simultaneously with the outputting of a switch-over signal fromthe internal control unit 26 to the switch-on valve 14, or else delayedby a preset period of time.

When monitoring the outlet flow, the outputting of a switch-over signalfor the switch-on valve 14 by the internal control unit 26 can likewisebe used as an initiator for recording actual flow data.

Like in the monitoring of the outlet pressure, actual data can berecorded once only or repeatedly when monitoring the outlet flow, and inthe repeated recording of actual data, regular time intervals can beused in particular.

Alternatively or in addition, the compressed air conditioning apparatus2 preferably offers the opportunity of basing the recording of theactual data on a trigger signal supplied by the connected electroniccontrol device 23, which trigger signal acts as an initiator. Thistrigger function of the external electronic control device 23 isparticularly advantageous in flow monitoring, because it offers thepossibility of monitoring the operating cycle of the load device A notonly as a whole, but also of monitoring one or more sub-cycles of theoverall operating cycle individually.

Flow is monitored in the working position of the switch-on valve 14. Inthis working position, compressed air normally flows from the compressedair source P to the load device A and there actuates one or more workingcomponents of the load device A which are activated by fluid power. Oneor more of these working components may for example be pneumatic drives.By comparing the actual outlet flow detected in the monitoring mode tothe associated second reference data 44, it is made easy to monitorwhether there is an increased air consumption during the operating cycleor during some of its phases or sub-cycles, which would indicate amalfunction of faulty working components.

In flow monitoring, too, the internal control unit 26 is in particulardesigned such that it outputs an electric diagnostic signal if detectedactual data deviate by a preset tolerance value from the associatedsecond reference data 44 recorded in the teaching mode. In the case offlow monitoring, the tolerance values are expediently stored in theinternal control unit 26 in the form of tolerance bands 45 a, 45 b,which flank the characteristics 44 a of the second reference data 44from above and below.

The tolerance values to be taken into account when generating thediagnostic signal can preferably be input individually into the internalcontrol unit 26. In this way, the used of the compressed airconditioning apparatus 2 can adapt the tolerance values and thus theoutputting of the diagnostic signal individually to requirements. Toinput the tolerance values, the inputting means 42 referred to above canbe used in particular, for example an arrangement of keys and/orswitches 42 and/or—for electronic inputting—an electric interface whichmay for example be represented by the first communication interface 28and to which a user interface and/or a personal computer (PC) canexpediently be connected.

The tolerance values are expediently input in the teaching mode. Thecompressed air conditioning apparatus 2 may, however, alternativelyoffer the possibility of altering the tolerance values while themonitoring mode is running, in order to respond flexibly to changingoperating conditions.

The teaching mode can expediently be parameterised individually usinginputting means 42. This can be done at the compressed air conditioningapparatus 2 itself by activating keys and/or switches 42, or else by theexternal electronic control device 23 using the serial bus connection33. This parameterisation can for example determine how often the actualdata in the internal control unit 26 are evaluated during the relevantoperating position of the switch-on valve 14. The changing of thetolerance values, for example the changing of the band width of thetolerance bands 45 a, 45 b, can also be subsumed under the tern ofparameterisation.

In the illustrated embodiment, the compressed air conditioning apparatus2 is provided with a further, second, communication interface 29 whichcan be used as a diagnostic interface and to which an electronic datareader 46 of the load control device 1 can in particular be connected atleast intermittently. Such an electronic data reader 46 for exampleallows the reading of measured actual data, in particular in combinationwith the associated reference data, so that, for example in the contextof flow monitoring, it is possible to verify either simultaneously orlater at which point of the recorded reference profile an irregularityhas occurred.

The internal control unit 26 is expediently designed or at leastprogrammable in such a way that it can, as a function of the comparisonresult determined by the comparator means 35, trigger at least onefurther action in addition to the outputting of a diagnostic signal. Inthe illustrated embodiment, this additional function is the initiationof a switch-over action of the switch-on valve 14. This is for exampleswitched from the working position into the blocking position if thereis no or at least no significant outlet flow in the outlet passage 22during a longer period of time, which can in particular be parameterisedfreely. Alternatively, it may be provided that the electric diagnosticsignal directly causes a switch-over action of the switch-on valve 14.

While in the cases described above the output of a switch-over signalfor the switch-on valve 14 can be initiated by the internal control unit26, the switching position of the switch-on valve 14 is otherwiseexpediently determined exclusively by the external electronic controldevice 23, which for this purpose feeds the required switch-over signalsinto the internal control unit 26 via the first communication interface28. The latter control unit exclusively acts as a transmitter ofswitch-over signals to the switch-on valve 14 without further processingthe switch-over signals received from the external electronic controldevice 23 in any way. In this way, the load on the microprocessor in theinternal control unit 26 is kept to a minimum.

The compressed air conditioning apparatus 2 can obviously be equippedwith further electric interfaces of any kind. In this way, any number ofswitching outputs can be made available, analogue values can be output,or a facility can be provided for a configuration by means of aconnectable personal computer. The preferably provided externalelectronic control device 23 is, as described above, expedientlyconnected using serial signal transmission technology by means of asuitable bus which may, among other features, correspond to theso-called IO link standard.

One advantage of the compressed air conditioning apparatus 2 lies in itseasy initial start-up. In principle, all that is required is theinstallation of the compressed air conditioning apparatus 2 into anexisting pneumatic system, followed by a teaching phase. The apparatusis now ready for operation.

Further advantages of the arrangement described above lie in the factthat the connected load device A can be pneumatically blocked withoutventing its supply line 22, 13, so that no energy is wasted in periodsof temporary non-operation. Nevertheless, the three-positionfunctionality of the switch-on valve 14 provides a facility for ventingthe connected load device A if required. The pressure sensor 24 providedcompares the pressure drop in the outlet passage 22 following itsblocking to a taught reference curve and outputs a diagnostic signal ifpressure drops too fast. This allows for the leakage monitoring of theload device A.

In normal operation, when the switch-on valve 14 is in the workingposition, the development of the flow value measured in the outletpassage 22 can be monitored in order once again to output a diagnosticsignal of this deviates from the taught value. This allows for theconsumption monitoring of the load device A.

If the compressed air conditioning apparatus 2 is implemented as a unit,it offers compact dimensions and combines a multitude of functionswithin a small space.

Finally, it should be pointed out that the compressed air conditioningapparatus 2 can be equipped with a reduced monitoring functionality bymonitoring either the outlet pressure or the outlet flow only. In thesecases, either the flow sensor 25 or the pressure sensor 24 can beomitted. However, the dual implementation of both monitoring measures inone and the same compressed air conditioning apparatus 2 is particularlyadvantageous, because it ensures that energy-relevant parameters aremonitored in a particularly effective way.

1. A compressed air conditioning apparatus comprising: an electricallyactuated switch-on valve which comprises a feed inlet connectable to acompressed air source, a vent outlet connected to the atmosphere and anoperating outlet and which can be switched into a working positionconnecting the operating outlet to the feed inlet and into a ventingposition connecting the operating outlet to the vent outlet; anapparatus outlet connectable to an external load device and connected tothe operating outlet of the switch-on valve via an outlet passage; apressure sensor suitable for measuring the outlet pressure prevailing inthe outlet passage and/or a flow sensor suitable for measuring theoutlet flow rate prevailing in the outlet passage; and an internalelectronic control unit which is connected in teens of signallingtechnology to the switch-on valve and to the pressure sensor and/or theflow sensor and which can be operated in a monitoring mode, wherein theswitch-on valve has a 3/3-valve functionality and can additionally beswitched into a blocking position in which its operating outletconnected to the apparatus outlet (7) is isolated both from the feedinlet and from the vent outlet, and wherein the internal electroniccontrol unit can in the blocking position and/or in the working positionbe operated in a teaching mode as an alternative to the monitoring mode,in which teaching mode a time-dependent pressure drop of the outletpressure can be determined in the blocking position and/or atime-dependent flow profile of the outlet flow rate can be determined inthe working position and these values can be stored in the form ofreference data in storage means of the internal electronic control unit,and wherein the internal electronic control unit comprises comparatormeans whereby actual data supplied by the pressure sensor and/or theflow sensor during the monitoring mode can be compared to the relevantreference data, and wherein the internal electronic control unitcomprises outputting means which can output a diagnostic signal as afunction of the comparison result of the comparator means.
 2. Acompressed air conditioning apparatus according to claim 1, wherein theapparatus is designed in the form of a unit.
 3. A compressed airconditioning apparatus according to claim 1, further comprising visualdisplay means and/or audible warning means which can be actuated on thebasis of the electric diagnostic signal.
 4. A compressed airconditioning apparatus according to claim 1, further comprising at leastone communication interface connected to the internal electronic controlunit to which can be connected an external electronic device forcommunication with the internal electronic control unit the at least onecommunication interface being designed as a bus interface.
 5. Acompressed air conditioning apparatus according to claim 4, wherein theat least one communication interface is of an electromechanical typeand/or the at least one communication interface is designed for wirelesssignal transmission.
 6. A compressed air conditioning apparatusaccording to claim 4, wherein the internal electronic control unit isdesigned for transmitting the electric diagnostic signal to at least onecommunication interface of the compressed air conditioning apparatus. 7.A compressed air conditioning apparatus according to claim 4, whereinthe internal electronic control unit is designed for transmittingswitch-over signals from an external electronic control device connectedto a communication interface to the switch-on valve, in such a way thatswitch-over signals fed in via the communication interface can betransferred directly to the switch-on valve without any processing bythe internal electronic control unit.
 8. A compressed air conditioningapparatus according to claim 1, further comprising inputting means foractivating and/or parameterising the teaching mode.
 9. A compressed airconditioning apparatus according to claim 8, wherein the inputting meanscomprise at least one key and/or at least one switch and/or at least oneelectric interface.
 10. A compressed air conditioning apparatusaccording to claim 1, wherein the actual data are recorded at a sametime interval as the associated reference data.
 11. A compressed airconditioning apparatus according to claim 1, wherein in the monitoringmode a switch-over signal intended for the switch-on valve and generatedand output by the internal electronic control unit or a trigger signaldelivered by an external electronic control device acts as an initiatorfor the recording of actual data.
 12. A compressed air conditioningapparatus according to claim 11, wherein the actual data can be recordedby the internal electronic control unit starting with the output of aswitch-over signal intended for the switch-on valve or thereafter with apreset time delay.
 13. A compressed air conditioning apparatus accordingto claim 11, wherein actual data of the pressure sensor are recordedstarting with or delayed after the output of a switch-over signalswitching the switch-on valve into the blocking position, in order toallow leakage monitoring by way of a comparison with the associatedreference data.
 14. A compressed air conditioning apparatus according toclaim 11, wherein actual data of the flow sensor are recorded once orrepeatedly starting with or delayed after the output of a switch-oversignal switching the switch-on valve into the working position, in orderto allow air consumption monitoring by way of a comparison with theassociated reference data.
 15. A compressed air conditioning apparatusaccording to claim 1, wherein the internal electronic control unittolerance values are or can be stored, which are taken into account whengenerating the electric diagnostic signal to be output, wherein thetolerance values can be present in the form of at least one toleranceband.
 16. A compressed air conditioning apparatus according to claim 15,wherein the tolerance values can be input individually and freelyselectable, using existing inputting means of the compressed airconditioning apparatus and/or via at least one electric interface of thecompressed air conditioning apparatus.
 17. A compressed air conditioningapparatus according to claim 1, wherein the internal electronic controlunit is designed for initiating a switch-over action of the switch-onvalve as a function of the comparison result of the comparator means.18. A load control device comprising at least one compressed airconditioning apparatus according to claim 1 and an external electroniccontrol device connected or connectable thereto.